The field of the invention is occupant restraint systems for use in vehicles. It is especially adapted for use in fast moving vehicles, such as aircraft or race cars. Such vehicles can subject the occupants to large accelerations/decelerations during unexpected, undesirable events, such as a violent maneuver or a crash. These accelerations/decelerations can lead to large displacements of the occupant""s body, which can result in the occupant""s body or head contacting structure or objects within the vehicle. This can result in serious injuries or possibly death. Specially designed seats and restraint systems are typically used to restrain the occupant, however, excessive body displacement can still occur during the undesirable events due to the wide range of human body types and sizes.
Restraint systems include inertia reels that are designed to prevent movement of the body during normal operation of the vehiclexe2x80x94such as reaching with the arms and turning of the torso. The inertia reels are also designed to lock (preclude webbing payout from the housing) when large accelerations or decelerations are detected. This minimizes the displacement of the seated occupant""s body to mitigate the potential for injury. Furthermore, the seated occupant is sometimes out of position or engaged in reaching or turning motions during the onset of an undesirable event. Even a securely restrained occupant seated firmly against the seatbelt with the restraint and inertia reel functioning perfectly, can still experience significant displacement (depending upon the severity of the event) and be seriously injured due to initial slack in the restraint, the compaction of the webbing on the inertia reel shaft, and induced stretch of the webbing material.
The device set forth below is intended to automatically retract the restraint webbing early in the event. By doing so, undesirable slack is removed and after the webbing is tightened, the occupant is held in the ideal upright seated posture, thereby minimizing the potential for serious injury. The device may be mounted directly to an existing inertia reel in the case of a retrofit, or configured as an integral feature of the inertia reel itself. Furthermore, the device is designed so that actuation will not injure the occupant it is intended to protect and ensure a safe exit from the vehicle after a crash. Also, non-crash, inadvertant actuation will not inhibit the occupant""s ability to continue to safely operate the vehicle, which is particularly crucial in aviation applications.
Although the initial application is in aviation vehicles, the device is also applicable to land vehicles where fast actuation is desired due to the severity of potential undesirable events (e.g. crashes involving high speed racing vehicles).
The present invention is for a pretensioner for tightening a restraint, such as a seatbelt, against an occupant upon the occurrence of a crash or other potential injury-causing acceleration or deceleration. The pretensioner has a locking reel to tighten the restraint when a signal directing such tightening is received. The pretensioner has a housing body with a cylinder having a rack with a piston end. The rack is held within the cylinder and includes an elongated arm having a piston at one end and a shaft extending toward a rack end of the cylinder. The shaft has a rack formed along a portion thereof and the rack is longitudinally movable within the cylinder. A pressure chamber is formed in the pretensioner body at the piston end of the cylinder. Means are provided for aligning the rack in the cylinder so that a longitudinal axis of the rack remains fixed during the movement of the rack. A pinion is held on a pinion shaft rotatably supported by the pretensioner body. The pinion shaft is connectable to the locking reel. A movable rack arm is held in a biased member against the terminus of the rack. This holds the rack so that the piston is nearest the piston end of the cylinder and the rack is out of contact with the pinion. In this way, the pinion can turn freely without contact with the rack until the rack is caused to move by pressure induced into the pressure chamber. The rack preferably has rack teeth along its upper surface and has a flat lower surface which rides on a shaft. As the rack moves, the movable rack arm, which is affixed to a shaft, causes a movable coupler arm to move. The movement of the movable coupler arm permits the release of a coupler, which is positioned between the pinion shaft and the locking reel.